Hot East. Cool West. Dreadful Midwest.

Hot sticky air hovers on the East Coast. Cool air is parked in the West. And when they repeatedly collide, it storms over an already saturated Iowa.

This has been the same weather pattern for weeks and it's led to tornadoes, thunderstorms, heavy rain and eventually record flooding.

Add to that La Nina in the Pacific Ocean, which some meteorologists think could be a factor. La Nina, which is the cooler side of El Nino, causes changes around the world, including more rain and snow in some of the Midwest.

Iowa's rivers and land probably could have handled the massive rain – more than 15 inches in the last two weeks in some places – if it weren't for the heavy snow in the winter and lots of rain in the early spring, said Rob Middlemis-Brown, director of the U.S. Geological Survey Water Center in Iowa City.

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That ground was saturated and rivers were already high when the latest batch of concentrated localized storms started in late May, leaving water nowhere to go but over river banks.

The Cedar River, like other flooding rivers in Iowa, eventually dumps into the Mississippi. The National Weather Service issued flood warnings Friday for the middle Mississippi River region.

For parts of Iowa and southern Wisconsin, this year's flooding is worse than the 1993 great Mississippi and Missouri river floods, said Ken Kunkel, interim director of the Illinois Water Survey. More rain is falling and in a shorter time now than in 1993. But for the entire Midwest, it was worse 15 years ago, he said.

That's because this year's flooding – while it has the same weather pattern as 1993 – is much more concentrated, Kunkel said. The flood 15 years ago was over a wider geographic area and lasted longer.

But give this year more time, he added. The 1993 flooding peaked in July and August. It's only June, so flooding for the broader region could be as bad as 1993 or worse if patterns hold, Kunkel said.